1. Field of the Invention
This invention relates to a drive device for a sewing machine, and, more particularly, to an improvement of a drive device that rotates a spindle on the sewing machine at a high speed by a clutch motor and at a low speed by an auxiliary motor.
2. Description of the Related Art
A sewing machine drive device of this type has been disclosed by Japanese Unexamined Utility Model Publication (OPI) No. Sho. 53-17468 (the term "OPI" as used herein means an "unexamined application"). In the drive device, the auxiliary motor is coupled to the spindle of the sewing machine. A foot pedal is directly connected by a rod to an operative lever which corresponds to a clutch lever for a clutch motor.
In the conventional sewing machine drive device, an auxiliary motor is coupled to a spindle of the sewing machine. However, coupling the auxiliary motor directly to the spindle of the sewing machine does not allow for proper rotation speed control. In order to overcome this difficulty, it is preferable to couple the auxiliary motor to a clutch motor.
In addition, the conventional drive device responds slowly to switching from a driving position to a stop position. The operating lever (that is, the clutch lever) is connected directly to the foot pedal, and the operation of the operating lever is caused directly by stepping on the foot pedal which results in a slower switching time.
Furthermore, even if the operating lever of the conventional drive device has a spring which pushes the operating lever toward the stop position, it is difficult for this feature alone to improve the switching character,